The fluorescence enhancement of the Eu-dibenzoylmethane(DBM)- cetylpyridinium-chloride (CPC) system was studied. The fluorescence intensity of the system can be greatly increased by Gd3+in the presence of triethanolamine(TEA). The optimum conditions for enhanced fluorescence of the Eu-Gd-DBM-CPC system were examined. It was a linear function of the Eu3+concentration in the range of 1.0×10−10∼1.0×10−8mol dm−3under the optimized conditions. The detection limit was 2.6 × 1011mol dm−3in an aqueous solution at pH=7.5∼9.5.